We compute the transverse energy-energy correlation (EEC) and its asymmetry (AEEC) in next-toleading order in s in proton-proton collisions at the LHC with the center-of-mass energy E c:m: ¼ 7 TeV. We show that the transverse EEC and the AEEC distributions are insensitive to the QCD factorization and the renormalization scales, structure functions of the proton, and for a judicious choice of the jet size, also the underlying minimum bias events. Hence they can be used to precisely test QCD in hadron colliders and determine the strong coupling s . We illustrate these features by defining the hadron jets using the anti-k T jet algorithm and an event selection procedure employed in the analysis of jets at the LHC and show the s ðM Z Þ dependence of the transverse EEC and the AEEC in the anticipated range 0:11 s ðM Z Þ 0:13.

This work presents an interpretation of high precision jet data from the ATLAS experiment in terms of exclusion limits for new coloured matter. To this end, the effect of a new coloured fermion with a mass m X on the solution of the renormalization group equation QCD is studied. Theoretical predictions for the transverse energy-energy correlation function and its asymmetry are obtained with such a modified solution and, from the comparison to data, 95% CL exclusion limits are set on such models.

We present an analysis with improved sensitivity to the light charged Higgs (m H + < m t − m b ) searches in the top quark decays t → bH + → b(τ + ν τ ) + c.c. in the tt and single t/t production processes at the LHC. In the Minimal Supersymmetric Standard Model (MSSM), one anticipates the branching ratio B(H + → τ + ν τ ) 1 over almost the entire allowed tan β range. Noting that the τ + arising from the decay H + → τ + ν τ are predominantly rightpolarized, as opposed to the τ + from the dominant background W + → τ + ν τ , which are left-polarized, a number of H + /W + → τ + ν τ discriminators have been proposed and studied in the literature. We consider hadronic decays of the τ ± , concentrating on the dominant one-prong decay channel τ ± → ρ ± ν τ . The energy and p T of the charged prongs normalised to the corresponding quantities of the ρ ± are convenient variables which serve as τ ± polariser. We use the distributions in these variables and several other kinematic quantities to train a boosted decision tree (BDT). Using the BDT classifier, and a variant of it called BDTD, which makes use of decorrelated variables, we have calculated the BDT(D)-response functions to estimate the signal efficiency vs. the rejection of the background. We argue that this chain of analysis has a high sensitivity to light charged Higgs searches up to a mass of 150 GeV in the decays t → bH + (and charge conjugate) at the LHC. For the case of single top production, we also study the transverse mass of the system determined using Lagrange multipliers. a

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